https://uvadoc.uva.es/handle/10324/23043 Ingeniería de Procesos a Presión - Comunicaciones a congresos, conferencias, etc. 2026-04-18T13:13:27Z https://uvadoc.uva.es/handle/10324/82985 Chitin is an abundant biopolymer of [-1,4-poly(n-acetyl-D-glucosamine)] units, produced by crustaceans, mollusks, insects, and fungi. Nowadays, chitin is discarded in massive amounts (6–8 million tons/year) as waste from the seafood industry, being underexploited as biomass resource[1]. Chitin is of great interest as a biocompatible and biodegradable material, gaining importance in the formulation of phytosanitary products, thanks to its elicitor activity in plants[2]. It is also considered as a source of oligosaccharides and biologically active monomers, N-acetylglucosamine (depolymerization) and glucosamine (deacetylation). Several studies have shown that chitin, like cellulose, can be dissolved and hydrolyzed in supercritical water (SCW) due to the change in its properties (water density and ionic product, among others); however, due to the high chitin crystallinity, this process occurs less easily[3]. The present work aims to investigate the mechanisms of chitin transformation in SCW medium (400°C and 25MPa), using ultrafast sudden expansion microreactors (SEMR) in a continuous system (residence time 0.1s - 2s). 2023-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/82983 The fishing and food industry generates large amounts of crustacean shells as waste from their processes. These shells contain 20-30% of chitin, 30-50% of minerals (mainly calcium carbonate - CaCO3), 30-40% of proteins and other compounds in smaller amounts, such as lipids and pigments. Chitin and its derivative, chitosan, are highly demanded products due to their interesting applications. Global valorization of crustacean shells may include protein recovery and development of applications for minerals. In the conventional process for the separation of chitin and its subsequent purification from the crustacean shells, three chemical processes are necessary: deproteinization, demineralization and decolorization, and chemical reagents potentially harmful to the environment are used for each of these steps. To avoid the drawbacks realated to chemicals, development of greener and more efficient processes are under development for the valorization of this waste biomass. In this context, this project aims to develop a biorefining process for the valorization of shrimp molting shells, by sequential fractionation with non-conventional techniques to obtain two differenciated products: 1) a protein concentrate and 2) a chitin-calcium carbonate composite that will be used as platform material for catalyst development and films production. 2023-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/82969 Chitin ((1,4)-β-N-acetylglucosamine) is the second most widespread bio-polymer worldwide. Its high crystallinity and low solubility limit the exploitation of its antimicrobial, non-toxic and biodegradable properties, among others. So far, batch reactors and residence times longer than 1min with sub-and supercritical water have been tested to depolymerize chitin. In this work, we investigate the influence of temperature and residence time on chitin transformation in sub- and supercritical water (25MPa, 350 °C to 385 °C), using ultrafast continuous reactors (0.3s to 12s). Within the range studied, chitin gasification above 30% was detected when operating at high temperature (T≥376 °C) and a long residence time (t≥5s). At these conditions, mean particle size of water-insoluble fraction was also reduced to ca. 280 nm. By-products such as glycolaldehyde, acetic acid and 5-HMF were identified in the water-soluble fraction, indicating the presence of side reactions. 2023-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/82968 This study aimed to apply microwave technique for the extraction of proteins from shrimp molt shell using water as the only solvent. The variables temperature, isothermal time, particle size, solid-liquid ratio (S/F) and stirring rate were studied to understand if they are significant variables. By varying the process parameters, it was possible to obtain an extraction yield of 16-31g/100g dry molt shell, extracted proteins of 3-7 g/100g of dry molt shell, and extracted amino acids of 0.5-3 g/100 g dry molt shell. In addition, isothermal time was found to be the variable with the highest influence on the extracted protein content. The obtained results indicated the variables temperature, isothermal time, and S/F as significant variables for protein extraction, within the selected range. 2023-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/82967 According to the Food and Agriculture Organization of the United Nations, by the year 2022, crustacean production represented 10% of all global production from fisheries and aquaculture. The shell of the shrimp represents approximately 47% (w/w) of the animal2. It is therefore a potential source of pollution in the production (aquaculture) or processing (food industry) process, when not properly disposed. Currently, shrimp shell is partially used to produce chitin and chitosan by harsh acid and alkaline treatments, however, they pose an environmental threat and avoid the valorization of other compounds of industrial interest, such as the liposoluble compounds, with emphasis on carotenoids2. The application of the supercritical fluid extraction technique with the cooking and conventional drying of shrimp shells as a pretreatment for the extraction of carotenoids has already been studied. Despite the advantages shown by this pretreatment to increase the extracted carotenoids by breaking their association with macromolecules, the process has the disadvantage of requiring long processing time and high energy consumption. However, for sustainable biorefining processes, faster and more efficient pretreatment processes are required. The microwave technique for pretreatment of the sample to increase the extraction yield has already been proven in the literature for other raw materials with shorter processing time compared to conventional methods4. Within this context, this work aimed to study the efficiency of the MW pretreatment for the combined cooking and drying process in relation to the conventional method. 2023-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/82913 Shrimp production generates the exoskeleton as one of the waste products due to the moulting process of the arthropods1. This shell can be valorised by the recovery of chitin, but it also has a high protein content (20-40%)2 with interest to be isolated. During the conventional chitin extraction process, these obtained proteins cannot be reused, due to the use of inorganic alkaline solvents3. In this context, this study aimed to use water as solvent for the extraction of proteins from shrimp molt shells by microwave assisted extraction. The variables temperature (T: 175 and 225 °C), isothermal time (t: 0 and 10), and solvent-feed ratio (S/F: 10, 20 and 40 mL/g) were studied to understand their effects in the extraction of the proteins and co-extraction of other compounds 2023-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/82912 Chitin is an abundant biopolymer of [-1,4-poly(n-acetyl-D-glucosamine)] units, produced by crustaceans, mollusks, insects, and fungi. Nowadays, chitin is discarded in massive amounts (6–8 million tons/year) as waste from the seafood industry, being underexploited as biomass resource1. Chitin has high interest as a biocompatible and biodegradable material, but also as a source of biologically active oligosaccharides and monomers, N-acetylglucosamine (depolymerization) and glucosamine (deacetylation). These monomers constitute nitrogen-containing building blocks and open the way to biorefineries of alternative biomasses, such as sea-wastes, to obtain molecules of interest, such as furan- or amine-based monomers. Several studies have shown that chitin, like cellulose, can be dissolved and hydrolyzed in supercritical water (SCW) due to the change in its properties (water density and ionic product, among others); however, due to the high chitin crystallinity, this process occurs less easily. 2023-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/82911 After cellulose, chitin is the second most widespread biopolymer worldwide. Its best-known applications, thanks to its antibacterial, toxicological and biocompatibility properties, are oriented to the medical and pharmaceutical industry, cosmetics, agriculture, and water treatment, among others. Being a biopolymer, chitin is formed by [ -1,4-poly(n-acetyl-D-glucosamine)] units, which can be treated to obtain oligomers and monomers, N-acetylglucosamine (depolymerization) and glucosamine (deacetylation). These monomers constitute nitrogen containing building blocks that open the way to sea-waste biorefinery for obtaining molecules of interest, such as furan-based monomers or amines1. Studies have shown that chitin, like cellulose, can be dissolved and hydrolyzed in sub- and supercritical water; however, due to its high crystallinity, this process occurs less easily2. Processes studied have used sub- and supercritical technology in batch-type systems as pre-treatments in enzymatic processes, managing to dissolve and even obtain monomers in times of up to 1 minute2. However, degradation compounds have been obtained or even the prevalence of side reactions competing with hydrolysis has been observed (depending on the reaction conditions). The present work shows the behavior of chitin in subcritical and supercritical media, seeking to understand the effect of water properties (density, viscosity, ionic product) at conditions surrounding the critical point; specifically, to investigate the reaction mechanism of chitin in SubCW and SCW media using ultrafast continuous reactors. 2023-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/82907 Chitin [β-1,4-poly(n-acetyl-D-glucosamine)] is the second most abundant biopolymer after cellulose, and it is produced by crustaceans, mollusks, insects, and fungi. Chitin has high interest as a biocompatible and biodegradable material, but also as a source of biologically active oligosaccharides and nanoparticles. The recalcitrant structure of chitin makes traditional processes use harsh acidic conditions to generate these products. In this work, the use of water at high temperature (270 to 400ºC) and pressure (20MPa) was studied to produce oligosaccharides and nanoparticles. The physicochemical properties of water (density, viscosity, diffusivity, ionic product, and dielectric constant) change dramatically below and above of the critical point (374 °C and 22 MPa) providing a tunable reaction medium, remarkably at subcritical medium (SubCW) ionic reactions are promoted due to the high ionic product while the low the concentration of [H+] and [OH-] at supercritical conditions (SCW) favor radical reactions. Furthermore, control on residence time is critical in such conditions: according to literature, formation of solid (char) and liquid (5-hidroxy methyl furfural) degradation compounds have even prevailed working in batch-type systems even at short times up to 1 minute. In this work, residence times as short as 0.1 to 8 s are explored thanks to a Press-Tech group designed facility working in continuous mode: heating and cooling down are achieved almost instantaneously by mixing an aqueous suspension of chitin at room temperature with hot pressurized water in “T” piece just before the micro-reactor (1.2-25 mL) and, afterwards, is cooled down by a sudden expansion valve at the outlet. 2025-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/82903 A green strategy employing only water as solvent has been adopted to obtain protein hydrolysates from residual shells of Litopenaeus vannamei generated as waste during the production of this species by aquaculture. The goal was to produce a protein hydrolysate through the fractionation of waste biomass, eliminating the need for conventional alkaline treatments and avoiding the environmental and operational issues associated with the use of strong bases. Subcritical water (sCW) refers to the water in the temperature range of 100–374℃ where high pressure (up to 220 bar) is applied to maintain water in the liquid state. At sCW conditions, the physico-chemical properties of water change significantly in comparison with water at ambient conditions; non-polar compounds can be extracted due to the changes of electrochemical properties, such as the decrease of dielectric constant and increase of ionic product of water. The ionic product of water increased from 10-14 at ambient temperature to 10-12 under subcritical conditions, increasing the concentrations of H+ and H3O- acting as an acid-like catalyst for hydrolysis reactions. Therefore, sCW can hydrolyze some compounds in matrices like shrimp shell, where proteins are released from the matrix and broken down into valuable peptides and free amino acids. A crustacean exoskeleton is constituted mostly by a three-layered cuticle of chitin (15-30%) with trapped minerals (40-60%), proteins (15-25%) and minor components like astaxanthin. 2025-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/82886 Shrimp aquaculture is a growing economic sector; it accounts for the 63% of global shrimp production [1] and indoor farming is gaining importance, mainly in USA and Europe, to produce high quality and sustainable seafood [2]. During shrimp production, molt residue is generated as shrimp replace their old shell with a new one. For a sustainable development of shrimp farming, particularly of inner one, the global valorization is of primary importance. Similar to exoskeleton of adults’ shrimp, molts are mainly composed of chitin (20-30%), minerals (30-50%, mainly CaCO3), proteins (15-30%), and minor components carotenoids like astaxanthin [3], in variable percentage depending on the species and level of maturity. Although, shrimp residue is conventionally used to produce chitin and chitosan, the process uses intensively inorganic solvents, generates high volume of wastewater and emission of carbon dioxide [3], and hinders the valorization of other fractions present in shrimp shell. In this work, ultrafast sudden expansion micro-reactors (UF-SEMR), developed in our group some years ago, are used under subcritical conditions for the selective recovery of the protein fraction from shrimp molts preserving the original chitin structure in the solid residue for further valorization. Various reactor volumes are employed to control residence time within the range of 1–20 s for temperatures from 180 to 270ºC, while pressure was kept constant at 20MPa. A 75% protein from the molt shell, quantified by the bicinchoninic acid assay (BCA), was extracted in only 19.3s at 208ºC with minimal degradation (no free aminoacids were detected by HPLC analysis). Additionally, molecular weight of protein hydrolysate will be also correlated with operating conditions. Further, chitin content, its molecular weight and acetylation degree (DA) will be evaluated in the solid product to assess its integrity. 2024-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/82883 Shrimp is, by far, the most consumed crustacean world wide with a global production of 9.4 million tonnes in 2022, with a share of 63% of aquaculture production [1]. During the production and processing, shells and other parts are generated as waste that account for aproximately 50% of the shrimp. The shells are interesting sources of chitin and chitosan, through a process mainly based in the use of inorganic solvents, harmful to the environment due to the use of high concentration and volume, and generating lots of wastewater [2]. Moreover, this process hampers the use of other fractions present in shrimp shell such as proteins, due to degradation by the alkaline inorganic solvent used [3]. Therefore, alternative cleaner processes are needed to develop sustainable crustacean biorefineries for global valorization of shrimp. In a previous group’s work, microwave technology has being applied for the extraction of proteins using only water in the range of 175-225 °C, demonstrating its potential as deproteinization solvent [4]. Ultrasonication is a technology that has been used as a pretreatment on chitin extraction from shrimp shells by other processes such as subcritical water hydrolysis [3] and fermentation [5]. However, up to our knowledge, there is not any study in the literature based in the ultrasound-assisted extraction (UAE) of proteins from shrimp shells as a whole fractionation step. For this purpose, the aim of this work is to study the effect of operational variables on the UAE of proteins from shrimp waste using only water as solvent. Temperature (0-65 ºC), Solvent/Feed ratio (10-60 mL/g), amplitude (60-100%), time (5-30 min) and cycle (0.6-1) has been selected for screening tests. A Box-Behnken approach will be performed to maximize protein extraction yield and minimize co-extraction. Proteins will be quantified by the bicinchoninic acid assay (BCA) and free amino acids by the ninhydrin method [4]. Co-extraction will be determined gravimetrically. Litopenaeus vannamei’s waste will be used as raw material. The suspension is sonicated by means of the UP400S Ultrasonic Processor (400 W, 24 kHz; Hielscher, Germany), equipped with a 22 mm titanium probe, with a maximum amplitude of oscillation of 100 μm, in a 200 mL jacketed vessel for temperature regulation. Temperature in the extraction vessel was monitored by a thermocouple. Energy consumption is continuosly measured. 2024-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/82880 Exploring renewable biomass and waste for higher-value products and energy is crucial for circular economy development. Crustacean shell wastes (exoskeletons from prawns, shrimp, crabs, and lobsters) are abundant (6-8 million tons/year) but currently underutilized, often disposed in landfills or dumped into the ocean, these wastes pose environmental and health risks [1]. Exoskeletons are primarily composed of chitin (20-30%), minerals (30-50%, mainly CaCO3), proteins (15-30%), and minor components carotenoids like astaxanthin [1] [2]. The growing interest in marine peptides (2–20 AA) for functional foods [3] necessitates efficient, selective fractionation processes using eco-friendly solvents and energy-intensified methods to valorize this waste. Subcritical water has been employed in batch mode to process shrimp shells for protein recovery; recent studies found that at 260 ºC and 5 minutes (isothermal time), 96% of the protein was removed from shrimp shells as hydrolizate [4]. However, it was not evaluate the potential presence of chitin degradation products in the liquid, since it has been demonstrated at temperatures slightly above (283ºC) and processing times in the same range [5]. Our group has developed ultrafast sudden expansion micro-reactors (UF-SEMR) with sub and supercritical-water for biomass continous processing, yielding excellent fractionation results for lignocellulose biomass [6]. The goal of this study is to utilize UF-SEMR under subcritical conditions for the selective recovery of the protein fraction from shrimp shells while preserving the original chitin structure for further valorisation. To achieve this, a water suspension of shrimp shells (1-10% wt.) is continuously fed into a continuous ultrafast hydrothermal plant. Heating is accomplished by mixing the compressed room temperature biomass suspension (0.5-1 kg/h) with a hot pressurized water stream (3-6 kg/h), reaching the desired temperature (140-300 ºC) just before entering the UF-SEMR. Instantaneous cooling is achieved through sudden decompression. Various reactor volumes are employed to control residence time within the range of 0.2–60 s. Supercritical hydrolysis is already established at an industrial scale [7]. Proteins will be quantified by the bicinchoninic acid assay (BCA) and free amino acids by the ninhydrin method in the liquid product. Chitin content, its molecular weight and acetylation degree (DA) will be evaluated in the solid product. 2024-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/35191 Hydrothermal fractionation is a well-known process for lignocellulosic biomass upgrading. It is based on the continuous treatment of biomass with hot pressurized water, converting the biomass major components (hemicellulose, cellulose and lignin) into soluble compounds. Thus, it is one of the most promising options to produce chemicals and energy from biomass since it only requires water and temperature. However, it is a highly complex process that involves a great deal of physical phenomena: biopolymer and oligomer cleavage, sugar production and degradation, acid releasing, homogeneous acid catalysis, solid-liquid mass transfers and porosity changes. For this reason, the development of a comprehensive kinetic model for biomass hydrothermal fractionation is a difficult matter. Despite these burdens, several modelling options that go from the simplest option, a first order kinetic model, to deeper and complete studies, can be found in the literature. These models are able to reproduce the experimental data of different biomasses in both, packed bed and batch reactors. Nonetheless, they are generally used for just one reactor or for one specific biomass, like spruce or wheat bran. Thereby, this work was aimed at developing an overall model for hemicellulose extraction, validating it with data from different packed bed reactors and for completely different biomasses. Additionally, this model included the whole set of physical phenomena. So, a novel reaction path way with all the physico-chemical process involved in the both phases, the liquid and the solid, was proposed. The model was obtained applying a mass balance for each compound in this mechanism and it was solved applying advanced numerical methods (orthogonal collocation over finite elements and Runge-Kutta with 8th order of convergence). Regarding kinetics, auto-catalytic expressions were selected since they have been demonstrated to be a suitable option to simulate quick changes in concentration profiles. On the other hand, the data of the hydrothermal fractionation were taken from 4 different reactors and using 3 biomasses (holm oak, wheat straw and catalpa) were used (0.1, 3, 6 and 40L). The temperature range was between 140 ºC and 215 ºC to focus the study on the hemicellulose extraction and the residence time was fixed around 5 min to promote extraction without degrading the hydrolysate. The model reproduced the experimental behaviour with average deviations between 6 and 50%. It is worth mentioning that the higher deviations were obtained when also the uncertainty of the experimental measure of the compounds was high. The simulated profiles included: oligomers, hexoses, pentoses, acetic acid, degradation products and pH. Furthermore, it is worth mentioning that the fractionation was mainly controlled by the soluble oligomers production and their hydrolysis kinetics. Therefore, it could be concluded that, for the cases studied, if temperature and pH profiles inside two different reactors are similar, their global behaviour will be also the same, independently of the biomass studied and reactor properties. Finally, it should be remarked that all the calculated parameters had physical meaning. 2018-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/35184 Wheat bran is an important by-product of the cereal milling industry and it has a great potential as raw material in a biorefinery. Wheat bran contains many important bioactive phenolic compounds, such as ferulic acid (FA), phytic acid, caffeic acid and flavonoids that can be recovered in a first step of a cereal biorefinery to increase economical benefit of the whole process. FA is the most abundant phenolic acid in the wheat bran, and it exhibits a number of potential applications such as natural antioxidant, food preservative/antimicrobial agent, anti-inflammatory agent, photoprotectant, and as precursor of vanillin (food flavor). FA seems to be part of the cell wall bounded via ester linkages to the structural polysaccharides, while dimers of ferulic acid can serve to cross-link hemicelluloses. Ferulic acid is unstable and can be oxidized in high temperature and it could be denature and reduced by using alkaline-hydrolysis. Release of FA from plant material is typically facilitated by alkaline and enzymatic hydrolysis. Alkaline-hydrolysis cannot be considered a green technology, is poorly selective and solvent consuming. Enzymatic-hydrolysis requires cocktails of enzymes (amylases, xylanases, proteases, feruloyl esterases) combined with bran pre-treatment and exhibits economical drawbacks and low extraction yield per unit of enzyme. The challenge is, therefore, to intensify the process by using green and short time techniques with high hydrolysis capacity to recover selectively the maximum amount of free FA and preserving the antioxidant activity of the extract. In this work, we present and discuss a strategy to maximize the recovering of free FA from wheat bran by using microwaves and subcritical water. This study presents the effect of various factors in a Microwave-Assisted-Extraction (MAE) with water: time, temperature and solvent/solid ratio, using Box-Benhken experimental design. MAE of wheat bran at 220ºC and 1 minute leads to the recovery of ca. 80% of the FA, that is a really high yield compared to that reported in the literature for enzymatic hydrolysis (15-35%) [1]. However, more than 70% of FA remains bounded to the cell compounds extracted under such conditions. Subcritical water in the range has been evaluated to complete the release of free FA. Temperatures in the range 250-320 ºC and time from 1 to 10 min have been studied at 150 barg and discussed using the severity factor. Under such conditions dissociation of water is very important, and hydroxyl groups act to the ester bond breakage. Results are discussed in terms of total FA extraction yield, Free FA extraction yield, TOC and total phenolic content and antioxidant capacity of the final hydrolysate. 2017-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/35151 Extraction and Hydrolysis of arabinoxylans have been studied using RuCl3 catalysts over different mesoporous silica supports. Acidity of the catalyst is a key parameter for these processes: the higher the Acidity, the higher the Yield. Ru+3 has demonstrated to be active, as it is a moderate Lewis acid. Arabinose is always faster released than xylose: Arabinose belongs to side chains and it is linked by beta-glycosidic bonds (weak). Xylose belongs to the backbone and it is linked by β -glycosidic bonds (strong). 2017-01-01T00:00:00Z